Not that "illustrated" books of a certain class were by any means unknown before that period.

Evolution of the game that became modern baseball is unknown before 1845.

"This was almost unknown as an injury in our region before this," he said.

He was still relatively unknown nationally before the primary season.

Or any others of her race, though they were unknown to our species before your little friend arrived.

But the exact severity of the problem was unknown to me until just before this meeting.

But she had departed for destinations unknown well before Kit's arrival.

It was almost unknown before the later 17th century, but thereafter became widespread.

The story was completely unknown to Big Finish before this.

Point technique is a relatively recent invention; it was unknown before the early 19th century.